A hearing aid, in general, comprises a housing or ear mold which contains a receiver, a microphone, electronic circuitry connecting the receiver and the microphone, and a battery for operating the electronic circuitry. The housing is an ear mold which fits into the ear canal of the user.
In a conventional hearing aid, the microphone converts incident sound waves into an analog electrical signal which is then processed to filter out unwanted noise etc., amplified, and coupled to a receiver or speaker which converts the electrical signal back to sound waves. The electrical signal processor may be an analog processor which operates directly upon an analog electrical signal. Alternatively, the analog signal may be converted to a digital signal and processed by a digital signal processor (DSP). Typically, the signal processing circuitry is designed to provide a particular frequency response in order to compensate for the type of hearing loss suffered by the user. For example, one common type of hearing impairment is the difficulty in hearing soft sounds at high audible frequencies. Thus, it is common for the signal processing scheme of a hearing aid to increase the gain of these high-frequency sounds relative to lower frequency sounds.
There has been a growing need for small, reliable, easy to use low-cost hearing aids. In particular, it would be desirable to be able to provide a low-cost hearing aid design that could meet the needs of the vast majority of users experiencing age related hearing loss.
One approach to meet these goals has been the development of low-cost, mass-produced hearing aids, including disposable hearing aids. The disposable hearing aid is of a structure that is so inexpensive to manufacture that it is possible to merely replace the whole hearing aid, rather than just the battery, when the battery runs out. Thus, the life of a disposable hearing aid is dependent on the life of the battery. Examples of disposable hearing aids are described in, for example, U.S. Pat. No. 5,881,159 to Aceti et al., U.S. Pat. No. 6,058,198 to Aceti et al., U.S. Pat. No. 6,473,511 to Aceti et al., and U.S. Pat. No. 6,865,279 to Leedom, and in U.S. patent application Ser. No. 09/804,978 to Leedom et al., and Ser. No. 10/688,099 to Leedom et al., the entire teachings of which are incorporated herein by reference.
A limiting factor on the development of high-quality, inexpensive hearing aids is that many of the component parts of these devices, such as the signal processing circuitry, remain relatively expensive. Thus, there is a need to further reduce the cost of hearing aids.